Here’s a LinkedIn reply from my friend Irvin West, who is a Symantec sales professional:
The seal rollout will be phased over a period of 2 weeks and be completed on April 30th. It requires no action on the part of existing merchants. During this rollout phase, we are gradually transitioning to the new seal globally. During the transition phase, end consumers may experience seeing either the existing VeriSign seal or the new Secured by Norton seal. This is expected behavior, and by April 30th all seal displays will have transitioned to the new format.
Nonetheless, I’m sure it’s just a matter of time until they’re all switched over.